Staying at Good Day was the best decision of our trip, our experience was nothing short of fantastic - so good that we decided to extend our stay with the hostel for the second half of our trip.
Location is great, next to Pratunam market, Platinum mall and very convenient to get around. Slight distance (<1km) to nearest BTS but taxi in BKK is def more worthwhile than train.
Hostel wifi connection is strong, ironically stronger than some 4-star hotel's wifi. All other aspects i.e. cleanliness, service response time, amenities, are wonderful. Only drawback is the lack of lift, not advisable to bring bulky luggages if you're keen to stay there.
Hosts and staff are helpful, lovely and well-versed in English. Last but not least - in-house café serves tasty breakfast and tea (not to mention how instagram-able the interior is)
Would love to go back next time I'm in BKK!